Cataract surgery outcomes in eyes with previous radial keratotomy

Laser vision correction after radial keratotomy: systematic review and meta-analysis

Laser vision correction for residual refractive errors in patients with previous radial keratotomy (RK) presents a challenging task. Different techniques have been used with varying outcomes. This study aimed to systematically review published articles on refractive surgeries in post-RK patients by conducting a search on PubMed, Scopus, and Web of Science. The final analysis included 35 studies that described a total of 888 eyes. Our systematic review and meta-analysis demonstrated a significant improvement in uncorrected distance visual acuity (UDVA) for photorefractive keratectomy (PRK), topography-guided PRK, wavefront-guided PRK, and femtosecond laser-assisted in situ keratomileusis (LASIK) while mechanical microkeratome LASIK did not yield such significant improvements. Moreover, our results suggest that post-RK patients with hyperopia had a significant improvement in UDVA, whereas no such improvement was observed in patients with myopia.

Radial keratotomy: background and how to manage these patients nowadays

In this review, we presented the principles of radial keratotomy (RK), its evolution, enhancement, and complications, and strategies to manage the consequences of RK in the present day. It is essential to understand the RK procedure f, the theoretical background that supported this surgery, the current effect on the cornea, and how to approach patients needing vision improvement. These patients are developing cataracts that need to be handled well, from the IOL calculation to the surgical procedure. Guided keratorefractive surgery is the most accurate procedure to improve these patient's vision and life. Nevertheless, some patients may need other approaches, such as sutures, penetrating keratoplasty, corneal rings, and pinhole implants, depending on the degree of irregularity of the cornea, ablation depth for guided surgery or if the sutures are open.

Accuracy of Traditional and Modern Formulas for Intraocular Lens Power Calculation After Radial Keratotomy Using Standard Keratometry

Purpose

To compare the accuracy of multiple traditional and modern intraocular lens (IOL) power calculation formulas in post-radial keratotomy (RK) patients undergoing cataract surgery.

Methods

This retrospective case series included 50 eyes with prior RK who underwent routine phacoemulsification surgery with single-piece acrylic IOL implantation (A constant = 118.8). Outcomes of multiple formulas were calculated. Included formulas were SRK/T, Holladay 1, Holladay 2, Haigis, Barrett True-K, Haigis and Barrett True-K (target refraction of 0.50 D), Barrett Universal II, Kane, PEARL-DGS, Shammas no history, DK SRK/T, DK SRK/T (target refraction of 0.50 D), Double K (DK) Holladay 1, and DK Holladay 1 (target refraction of 0.50 D). Averages of multiple combinations of best-performing single formulas were calculated. Primary outcome is mean absolute error (MAE).

Results

Haigis (with -0.50 D target refraction) and DK SRK/T showed the lowest mean and median absolute errors (MedAE) followed by Haigis, Barrett True-K, and Barrett True-K (with -0.50 D target refraction). Combinations of 3, 4, or 5 of best performing single formulas yielded good results with >60% of cases within +0.50 D of intended refraction and MAE around 0.50 D. The best performing formulas with flatter K readings were PEARL-DGS and Haigis (with additional -0.50 D target refraction) with MAE of 0.72 + 0.71 D and 0.70 + 0.70 D, respectively, followed by Barrett True-K (with intended -0.50 D target refraction) with MAE of 0.75 + 0.63 D.

Conclusion

Using an average of three or more Haigis (with -0.50 D target refraction), the Barrett True-K, DK Holladay 1, and DK SRK/T formulas showed better outcomes than using a single formula for IOLMaster 700 standard K readings. The PEARL-DGS formula showed better accuracy in eyes with flatter K readings (<38 D).

Comparison of the accuracy of three intraocular lens power calculation formulas in cataract patients with prior radial keratotomy

PURPOSE

To compare the accuracy of three intraocular lens (IOL) formulas in Chinese cataract patients with prior radial keratotomy (RK).

METHODS

Medical records of cataract patients with prior RK at Beijing Tongren Hospital were retrospectively analysed. The absolute error (AE) was calculated as the absolute difference between the actual postoperative spherical equivalent and the predicted spherical equivalent. The AE and percentages of eyes with AE within 0.5D, 1.0D, and 2.0D for three formulas [Barrett True-K, Holladay 1 (D-K), Haigis] were calculated and compared.

RESULTS

Forty-seven eyes of 28 cataract patients were included. The Median AE (MedAE) was significantly different among the three formulas (P < 0.001). The MedAE was lowest for the Barrett True-K formula (0.62), followed by the Haigis (0.76), and Holladay 1 (D-K) (1.16). The percentages of eyes with AE within 0.5D, and 1.0D were significantly different among the 3 formulas (P = 0.009, and P < 0.001). The Barrett True-K formula achieved the highest percentages (46.8%) of eyes with AE within 0.5D. Haigis achieved the highest percentages (70.21%) of eyes with AE within 1.0 D.

CONCLUSIONS

Barrett True-K is the most accurate IOL power calculation formula among the 3 formulas and Haigis is an alternative choice. Considering the relatively lower accuracy of IOL formulas in cataract patients with prior RK, newer and more accurate IOL formulas are desirable.

Intraoperative aberrometry: an update on applications and outcomes

PURPOSE OF REVIEW

There is now a large body of experience with intraoperative aberrometry. This review aims to synthesize available data regarding intraoperative aberrometry applications and outcomes.

RECENT FINDINGS

The Optiwave Refractive Analysis (ORA) System utilizes Talbot-moiré interferometry and is the only commercially available intraoperative aberrometry device. There are few studies that include all-comers undergoing intraoperative aberrometry-assisted cataract surgery, as most studies examine routine patients only or atypical eyes only. In non-post-refractive cases, studies have consistently shown a small but statistically significant benefit in spherical equivalent refractive outcome for intraoperative aberrometry versus preoperative calculations. In studies examining axial length extremes, most studies have shown intraoperative aberrometry to perform similarly to preoperative calculations. Amongst post-refractive cases, post-myopic ablation cases appear to benefit the most from intraoperative aberrometry. For toric intraocular lenses (IOLs), intraoperative aberrometry may be used for refining IOL power (toricity and spherical equivalent) and alignment, and most studies show intraoperative aberrometry to achieve low postoperative residual astigmatism.

SUMMARY

Intraoperative aberrometry can be utilized as an adjunct to preoperative planning and surgeon's judgment to optimize cataract surgery refractive outcomes. Non-post-refractive cases, post-myopic ablation eyes, and toric intraocular lenses may have the greatest demonstrated benefit in intraoperative aberrometry studies to date, but other eyes may also benefit from intraoperative aberrometry use.